高強高耐蝕性釬焊鋁合金材料的開發(fā)

材料科學論文編號:CL015  論文字數(shù):20403,頁數(shù):38

高強高耐蝕性釬焊鋁合金材料的開發(fā)

目   錄
第一章 緒論 1
1.1 研究背景 1
1.2 汽車熱交換器鋁制化 2
1.3 鋁合金熱制生產(chǎn)技術 4
1.3.1 國內熱軋技術現(xiàn)狀 4
1.3.2 影響熱軋顯微組織的主要因素 6
1.4 熱變形行為研究模型簡介 7
1.5 金屬高溫塑性流變行為的研究內容 10
1.5.1 流變應力 10
1.5.2 動態(tài)回復 10
1.5.3 動態(tài)再結晶 12
1.6 本文研究目的、研究內容及研究路線 14
第二章 實驗方案 15
2.1 實驗材料 15
2.2 實驗方法 15
2.3 顯微組織觀察 16
第三章 結果分析 17
3.1 高溫熱變形真應力-真應變曲線 17
3.2 流變應力方程 18
3.2.1 應變速率，變形溫度，流變應力之間的本構方程 18
3.2.2 本構方程中相關系數(shù)的求解 19
3.2.3 本構方程 23
3.3 溫升修正 24
3.4 誤差分析 25
3.5 高溫熱變形組織研究 26
3.5.1 不同位置的顯微組織對比 26
3.5.2 變形溫度對顯微組織的影響 27
3.5.3 變形速率對顯微組織的影響 28
第四章 結論 30
致    謝 31
參 考 文 獻 32

摘   要
 為了滿足市場對鋁熱交換器用釬焊鋁合金材料的性能要求，同時又要規(guī)避受多項歐美國家注冊專利保護，急需開發(fā)一種新型鋁合金，使其耐腐蝕性能、力學性能和工藝性能達到或超過所謂“長壽命”鋁合金材料的性能指標。本文通過研究一種新型高強高耐蝕性釬焊鋁合金的熱變形行為，獲得材料真實應力應變曲線，建立熱變形本構關系，為優(yōu)化合金后續(xù)熱軋工藝提供材料數(shù)據(jù)，以及對合金熱軋變形組織和性能的預測分析。本文在Gleeble-1500熱模擬機上，采用圓柱體軸對稱等溫壓縮試驗，對一種新型高強高耐蝕性鋁合金高溫流變應力進行了研究。實驗過程變形溫度為350 ℃~550 ℃，應變速率為0.01 s-1~10 s-1，變形后立即進行水淬。主要研究內容如下：
 1. 鋁合金的真應力-應變曲線出現(xiàn)明顯的穩(wěn)態(tài)變形特征。在低應變速率條件下應力迅速增大，無明顯峰值，到達一定值后便趨于穩(wěn)態(tài)變形。在較高應變速率下出現(xiàn)一個明顯的峰值，且其明顯大于其后的峰值，隨后流變應力出現(xiàn)較大下降及周期性波動，最后也趨于穩(wěn)態(tài)變形，表現(xiàn)出不連續(xù)動態(tài)再結晶特征。
 2. 本構分析表明：可以采用雙曲正弦來描述鋁合金高溫熱壓縮變形流變行為，其熱變形激活能為154.3402 kJ/mol。
 3. 誤差分析表明：計算峰值應力與實測峰值應力之間的相對誤差基本在±10%之內，平均相對誤差為3.37%，吻合較好；溫升修正前后的峰值應力變化很小。
 4. 對顯微組織的研究表明：在變形過程存在變形不均勻性，變形溫度的升高和變形速率的增大，有利于再結晶的發(fā)生。
 
關鍵詞：釬焊鋁合金；熱壓縮變形；本構方程；動態(tài)再結晶

Exploitation on brazing aluminum alloy with high strength and high corrosion resistant
Abstract
 In order to meet the market requirements of brazing aluminum alloy for automobile heat exchangers,and avoid a number of registered patent protection in European countries,it is necessary to develop a new aluminum alloy ,so that the corrosion resistance, mechanical properties and process performance meets or exceeds the so-called "long life" aluminum alloy.In this present,the hot deformation behaviors of a new brazing aluminum alloy was studied by means of compression deformation tests on Gleeble 1500 machine at strain rates ranged between 0.01s-1~10s-1 and deformation temperature 350℃~550℃,and associated structural changes were studied by observations of metallographic . The results are shown as following:
 1. The true stress-true strain curves of brazing aluminum alloys appears steady-state deformation features apparently. At low strain rate, the true stress increases with true strain rapidly and enters a steady state after reached peak flow. At high strain rate, the true stress decreases sharply after the peak, then the curves enter steady-state deformation stage.
 2. Constitutive analysis suggestes that the peak stress can be represented by a Zener-Hollomon parameter in the hyperbolic-sine-type equation, with the hot deformation activation energy of 162.128 kJ/mol.
 3. Error analysis shows that relative errors between calculated peak stress and measured peak stress are roughly within ±10%,and average relative errors was 3.37%.The peak stress changed very little after temperature correction.
 4. The microstructural shows that inhomogeneous deformation was appeared. it is benefit for recrystallization with the increase of deformation temperature and deformation rate.
 
Key words: Brazing aluminum alloy;Hot compression deformation;Consitutive relationship;Dynamic recrystallization